My aim is to have a scaled background on iOS/Android that doesn\'t have to rescale after user scrolls down (and the address bar disappears). I found several questions with u
I feel your pain. If you look carefully at the example you found where there was no white space problem (http://www.heartkids.co.nz) - the answer was there, but hard to find unless you know what you are looking for.
You'll see they applied a 2d transform on the background image. In most cases applying either a 2d or a 3d transform on fixed divs with background images gets rid of unwanted white space like this.
This CSS should remove that annoying white bar. Cheers.
.background-img {
transform: translate3d(0,0,0);
}